Ever since upgrading to Lightroom CC 2015 (LR 6), the application hangs regularly. I am running OSX 10 and never had any trouble with LR 5.

The hanging happens randomly after some arbitrary amount of time. After running the app from the terminal (Adobe Lightroom.app/Contents/MacOS/Adobe Lightroom) I have seen the following logging messages displayed:

CGContextRestoreGState: invalid context 0x0. This is a serious error. This application, or a library it uses, is using an invalid context and is thereby contributing to an overall degradation of system stability and reliability. This notice is a courtesy: please fix this problem. It will become a fatal error in an upcoming update.